Keldon warriors don't need signals to tell them when to attack. They need signals to tell them when to stop.

ケルドの戦士には、戦いを始めるための合図は必要ない。彼らに必要なのは、戦いを止めるための合図だ。

ラッパの一吹き

ターン終了時まで、攻撃クリーチャーは＋２/＋０の修整を受ける。

凯尔顿战士不需要施令进攻，但却需要停手的讯号。

号角震天

进行攻击的生物得+2/+0直到回合结束。

Trumpet Blast

Attacking creatures get +2/+0 until end of turn.

The sound of the trumpets lights a fire in the hearts of the bold and snuffs the courage of the cowardly.

Core Set 2019

"Do you hear that, Sarkhan? The glory of the horde! I made a legend from what you abandoned."
—Zurgo, khan of the Mardu

Battlebond

Masters 25

Iconic Masters

Conspiracy: Take the Crown

An "attacking creature" is one that has been declared as an attacker this combat, or one that was put onto the battlefield attacking this combat. Unless that creature leaves combat, it continues to be an attacking creature through the end of combat step, even if the player it was attacking has left the game, or the planeswalker it was attacking has left combat.

Even though Trumpet Blast affects only attacking creatures, the bonus will remain for the rest of the turn.

Only creatures that are attacking as Trumpet Blast resolves will receive the bonus. In other words, casting it before you've declared attackers usually won't do anything.